Fluoride release in vitro from various glass ionomer cements and resin composites after exposure to NaF solutions

The release of fluoride from 1) discs made from five glass ionomer cements and two composites, and 2) the same discs after exposure to different NaF solutions, were studied. The specimens were placed in distilled water for 10 wk. After 24 h and then once a week, the specimens were transferred to fresh distilled water. After 5 wk, the specimens were divided into four groups and exposed to 0, 0.02, 0.2 and 2% NaF solutions for 5 min. The fluoride release was highest during the first week after preparation, after which it decreased sharply and then more slowly. The amount of fluoride released was ordered: liner/base > restorative glass ionomer > composites. The composites released significantly less fluoride than the glass ionomer cements. After exposure to NaF, the fluoride release was significantly higher for the silver cermet material than for the other glass ionomers tested. From a clinical point of view, the results from this study imply that glass ionomer restorations may act as intraoral devices for the controlled slow release of fluoride at sites at risk for recurrent caries.